1. Field of the Invention
The present invention involves the field of Magnetic Resonance Imaging (MRI). More particularly, the present invention involves a system and method for imaging regional deformation of tissue.
2. Discussion of the Related Art
Improvements in medical imaging technologies, such as MRI and ultrasound, have made it possible to image internal anatomical features in ways that show both structure and motion. Better diagnosis of certain medical conditions, such as heart disease, generally requires imagery that may be acquired quickly, and that provides information pertaining to both anatomical structure as well as function. Accordingly, there is an ongoing need for quantitative imaging of various tissue regions, such as the heart or other organs, which are observer independent. As used herein, observer independence means that the images capture the tissue as it nominally functions and involves minimal interaction with the mode of imaging. MRI is a good example of observer independent imaging.
As an example, observer-independent quantitative imaging of regional deformations in muscle tissue, such as the heart, may better enable diagnosis of coronary disease. Further, observer-independent quantitative imaging for tissue characterizations such as elastography may enable identification of tumors in surrounding tissue where it is impractical to apply external pressure, such as the chest cavity.
Magnetic Resonance Imaging (MRI) has become a leading means of imaging for noninvasive diagnostics. By operating in regions of the electromagnetic spectrum that are benign to tissue, MRI imagery may be acquired repeatedly without danger to the patient. Also, the advent of vast and relatively inexpensive computational power has enabled MRI imagery to be acquired in real time or near real time. Further, advances in MRI pulse sequencing, gradient magnet control, and signal processing algorithms have improved the volumetric spatial resolution and dynamic range of acquired imagery. As used herein, the term “imagery” may refer to a single image or multiple images.
Related art approaches to strain imaging include Strain Encoded imaging (SENC), which is an MRI technique for imaging regional deformation of tissue, such as the heart muscle. However, related art developments in MRI, such as SENC imaging, are not able to provide high quality imagery of tissue that includes a quantitative measure of tissue deformation.
Non-MRI medical imaging technologies are generally not well suited for observer-independent imaging. These technologies, such as ultrasound, may involve invasive devices or cutaneous probes that may apply pressure to the patient's body in the vicinity of the tissue being imaged. As such, other imaging technologies may interfere with the function of certain organs by applying pressure, causing tissue deformations that may interfere with the motion and function of the tissue being imaged.
Quantitative imagery of tissue deformation requires the ability to provide sufficient dynamic range of deformation. As used herein, dynamic range refers to resolution and linearity in frequency and intensity. Further, providing quantitative deformation imagery for different tissue types requires the ability to adaptively select the appropriate dynamic range for the tissue region of interest.